So, I'm trying to get a concept drawn up for this aerial predator, taking a lot of inspiration from Barlowe's Expedition and its Skewers. I would like to give it a unique mechanism for in-flight propulsion, but I am having trouble thinking of what might fit for it. Ecologically it'd climb to great heights and then dive, potentially using its propulsion mechanism to continually build speed until it finally impacts its prey.


4 Answers 4


Sidewinding up through the air.

Sidewinding is a form of locomotion used by certain desert snakes. A loop of body is stationary on the sand and used as a base to throw another loop of body forward through the air.

In the resultant movement, the snake's body is always in static (as opposed to sliding) contact when touching the ground. The head seems to be "thrown" forward, and the body follows, being lifted from the prior position and moved forward to lie on the ground ahead of where it was originally. Meanwhile, the head is being thrown forward again. In this way, the snake slowly progresses at an angle, leaving a series of mostly straight, J-shaped tracks. Because the snake's body is in static contact with the ground, without slip, imprints of the belly scales can be seen in the tracks, and each track is almost exactly as long as the snake.

https://en.wikipedia.org/wiki/Sidewinding sidewinder gif

Your creatures use a similar mode of locomotion, but use control over their serpentine body shape to affect air resistance. The "stationary" loop is flattened into a ribbon to provide maximum air resistance. The snake pushes against the resistant flap loop to throw wedge-shaped aerodynamic body parts upwards through the air. Then those body parts flatten and the previous flattened loop becomes aerodynamic and is thrown forwards.

These snakes climb through the air rather than gliding. Once high enough they glide downwards in the manner of flying snakes. Real flying snakes of course must gain altitude by climbing trees. The proposed animal uses the same undulatory mechanism to "climb" the air.

  • $\begingroup$ This is a supremely novel method of going about it and I really like that. This would work well for more serpentine predators for sure. The initial concept involves a creature with a more wide, triangular, flat body shape, but I forgot to clarify that. Thank you very much! $\endgroup$
    – Hauki
    Commented Feb 3, 2021 at 22:53

Jet propulsion:

If I'm reading your question the right way, you want a propulsion system to increase dive speed, not the ability to climb slowly. For this, aerodynamics are more like a bullet and being light stops being an issue. But impacting the ground at terminal velocity plus whatever speed you can add with your propulsion is a real concern. From the look of the fliers in your example, you seem to be missing the obvious propulsion system.

So let's go with something a little more like a bullet - say, a flying Squid. WHAT?!!? Squid can't fly! Yes, they CAN. Currently, they can't soar like the birds, but there really isn't a lot of pressure/opportunity for that niche. But maybe in your world, there was.

Squid don't have bones (a plus for sudden collision with a prey animal at high speed) but they can have hard parts like beaks and shell. This means they could have a shell acting like a harpoon to impale an animal on impact. With tentacles, they might even be able to use a tool like a stick for this lethal strike function.

Squid currently use water as their propellant for their bio-jet propulsion. If a squid evolved to take up an airborne role, however, they might huff and puff air, and/or reserve water for when they really need acceleration. You could imagine a squid developing a lung to extend out-of-water time, tough skin, and a VERY flat body design that could be reshaped back into a classical torpedo shape for dive bombing. Extend the design: they have been seen flapping their fins, and this could allow for a slow, clumsy ascent, torpedo down for impact (in or near water, ideally) and use their jet in a rocket-like manner (after refiling with water, or just air) to launch themselves airborne again.

But if you don't like squid, then this same propulsion mechanism could be used to suddenly accelerate anything you want to use enough parallel evolution on. So blast off with a jet-powered predator diving faster than anything else on (whatever planet you're using)!



Sophisticated biological pulsejet. Plus gliding.

What I mean by this is, the picture that you've linked to:

enter image description here

Copyright Wayne Douglas Barlowe 1990

There are intake nozzles clearly depicted, and ridges leading to outputs, out-gassing for thrust.

This implies a method of turning volatile combustibles into a means of propulsion.

I posit that this could be hypothetically achieved by the burning of hydrocarbons in the following way:

First there is the ignition, an oil is secreted into the area after the mouth of the combustion chamber as figure 1:

enter image description here

Wikipedia under CCSAL 2021

The ignition in figure 1 could be achieved through dieseling (the mixture of air and oil is compressed by muscular contractions until it reaches the temperature and pressure required for it to spontaneously combust) like the way a derv engine works.

This starts-up the process, and heats the local tissues of the beast. They contain glands like the preen oil glands of birds which produce oils, rhythmically pulsating to keep the reaction going

Who'd have thought, diesel powered dinosaurs are now to be found in your skies, terrifying the local wildlife.

As an aside, this seems like a (more or less) natural progression of therapod evolution which might happen instead of the boring old flappy birds we have today.

  • $\begingroup$ I went with a very similar approach, although the pulsejet is particularly spectacular. Wouldn't that be kind of energy-intensive? still, +1 $\endgroup$
    – DWKraus
    Commented Feb 3, 2021 at 22:54
  • $\begingroup$ Not certain about the scale of the thing, also not certain how much fat I'm carrying around at the moment, but if rendered I dare say I'd propel a family hatchback a few thousand kilometers. Suppose all that was in a relatively lean animal the size of a Quetzalcoatlus (or bigger), with all the fat directed into oil glands for propulsion. @DWKraus $\endgroup$ Commented Feb 3, 2021 at 22:59
  • $\begingroup$ I wonder if you had a lighter-than-air predator with a stabbing weapon, filled with hydrogen. Ascend slowly to height, maintain flight via buoyancy for long periods, then using the gas for acceleration. The body plan shifts from non-aerodynamic (floating) to the smaller, more aerodynamic (diving). A miss could be a real problem, and the time on ground would be very vulnerable. $\endgroup$
    – DWKraus
    Commented Feb 3, 2021 at 23:00
  • $\begingroup$ True (maybe you can ask a different question using that), but look at the wingspan of the OP's linked image, does it look like a floater or a glider with jets. @DWKraus $\endgroup$ Commented Feb 3, 2021 at 23:02
  • $\begingroup$ The image is from Wayne Douglas Barlowe's Expedition, as referenced in the OP, which was published in 1990. $\endgroup$
    – notovny
    Commented Feb 4, 2021 at 11:25

How about a gravity bomber?

The organism can be as simple in structure as a gas-filled jellyfish. It just.... floats around on the wind.

When it detects prey passing below, it farts out its buoyant gas, and plummets straight down like a brick.
Smashes into the prey, and kills it either through impact or via spearlike appendages, or venomous stings like a jellyfish. Then slowly reinflates as it digests the prey, rising back up to await another victim.

Not much in keeping with your vision of a swift apex predator, but it might be an interesting almost-inanimate predator for background color.


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